I have transited several times and landed once at the local Class D airport.. I stopped at a taxiway turnoff then pushed the glider past the hold short line then contacted ground control and "taxied" to the ramp. This airport is a contract tower and they are happy for any action that increases their traffic count.

I haven't had a chance to land at the Class C airport nearby but have talked to approach control many times when soaring nearby. My glider is transponder equipped.